to dig your own grave;  to bring calamity upon oneself;  to put your foot in it
 to perform anal sex;  to bugger;  to sodomize;  to crash one's car into the back of another
 to perform anal sex;  to bugger;  to sodomize;  to crash one's car into the back of another
 to perform anal sex (between men);  to bugger;  to sodomize;  to crash a car into the back of another (usu. used in the passive voice);  to rear-end
 to perform anal sex (between men);  to bugger;  to sodomize;  to crash a car into the back of another (usu. used in the passive voice);  to rear-end
 to each their own;  different strokes for different folks;  cut your coat to suit your cloth; (lit.) a crab digs a hole like its own shell
 to fail to make timely preparations; (lit.) to not dig a well until one is thirsty